Each cell inside a battery consists of a liquid, paste or solid "electrolyte," a "positive electrode," and a "negative electrode." The electrolyte is an ionic conductor; one of the electrodes reacts, producing electrons, while the other accepts electrons. When the electrodes are connected to a device to be powered (called a load) an electrical current flows. ("Battery," 2007) As an example, in one cell of a lead-acid battery used in automobiles, the process producing the current takes place as follows:

One plate inside the cell is made of lead; the other plate is made of lead dioxide, and it contains a strong sulfuric acid electrolyte in which both plates are immersed.

Lead combines with SO4 to create lead sulfate (PbSO4) plus one electron.

Lead dioxide, hydrogen ions and SO4 ions, plus electrons from the lead plate, create PbSO4 and water on the lead dioxide plate.

As the battery discharges, both plates build up PbSO4 (lead sulfate), and water builds up in the acid. (Brain, 2007)

The reaction can be reversed by applying current to...

(Ibid.)
Conclusion: As we saw in this paper, batteries provide us with power by converting chemical energy into electricity. They are used in almost every commonly used device such as cars, computers, cell phones, and MP3 players; hence battery is one of the most useful inventions ever made.

References

Battery." (2007). Article in Encyclopedia Encarta Online. Retrieved on April 3, 2007 at http://encarta.msn.com/encyclopedia_761577714/Battery.html

Brain, M. (2007). "How Batteries Work." How Stuff Works. Retrieved on April 3, 2007 at http://www.howstuffworks.com/battery.htm

How Do Batteries Work?" (n.d.) BBC Rough Science Library. Retrieved on April 3, 2007 at http://www.open2.net/science/roughscience/library/batteries.htm

Battery